Orphenadrine (sold under many brand names)[1] is an anticholinergic drug of the ethanolamine antihistamine class; it is closely related to diphenhydramine.

[4] Orphenadrine and other muscle relaxants are sometimes used to treat pain arising from rheumatoid arthritis but there is no evidence they are effective for that purpose.

Common side effects include dry mouth, dizziness, drowsiness, constipation, urine retention, blurred vision, and headache.

[8] Continuous and/or cumulative use of anticholinergic medications, including first-generation antihistamines, is associated with higher risk of cognitive decline and dementia in older people.

[9][10] Orphenadrine is known to have these pharmacological properties: George Rieveschl was a professor of chemistry at the University of Cincinnati and led a research program working on antihistamines.